S形进气道锤击波荷载特性分析

Analysis of hammer shock load characteristics in S-duct

利用基于改进的延迟分离涡模拟(IDDES)方法,对亚声速和超声速来流条件下某S形模型进气道进行了非定常计算,研究了发动机喘振所产生的瞬时高压波形对锤击波传播规律的影响.结果表明:锤击波产生后沿进气道迅速向前传播,运动过程中锤击波的运动速度基本保持不变,但强度不断增强.同时受气流离心力的影响,S形进气道弯曲段半径较大一侧壁面受到的锤击波气动荷载值更大.发动机喘振所产生的瞬时高压的加载梯度增加使得锤击波传播速度及强度增强,而压力卸载方式对锤击波强度的影响不明显.在亚声速和超声速来流条件下,增加瞬时高压峰值均使得锤击波荷载强度显著增强,并近似符合二次函数分布规律,而且超声速来流条件下锤击波强度较亚声速来流更强.

To analyze the effect of instantaneous high pressure profile caused by engine surge on the hammer shock propagation, an S-duct model was simulated under conditions of both subsonic and supersonic inflow, based on improved delayed detached eddy simulation （IDDES） method. Results showed that when hammer shock was generated, it propagated upward along the inlet rapidly with approximate constant speed and the strength of hammer shock increased. Meanwhile, the aerodynamic load of S-duct inner wall was uneven under the influence of centrifugal force field; the aerodynamic load on side wall with the larger radi- us was greater. Increasing the pressure loading gradient led to quicker hammer shock propa- gation speed and enhanced strength, however different unloading pressure profiles had no obvious effect on the hammer shock propagation speed and strength. Under both subsonic and supersonic inflow conditions, the intensity of hammer shock increased with the growth of maximum value of instantaneous high pressure, approximately matching the quadratic function distribution law. The hammer shock intensity of supersonic inflow was greater than the subsonic inflow.